The present invention relates to an image recording and/or reproducing apparatus capable of recording and/or reproducing an optical image of, for example, an original document or scenery in the form of an electrostatic pattern. More particularly, the invention is concerned with a simple and light-weight apparatus capable of recording the optical image in the form of electric signals and/or outputting the same to an external device in the form of electrical signals.
Hitherto, various image recording systems have been proposed, including an electrophotographic system in which an electrostatic latent image formed through an optical system on a copying medium is developed by a liquid or dry toner and is then transferred to a recording medium, as well as a system in which an original image is read by a digital photoelectric device making use of a CCD (Charge Coupling Device) and converted into electrical output signals.
The image recording apparatus making use of electrophotography enables an image to be formed with high degrees of density and clarity in a multiplicity of gradations, but suffers from the disadvantage that the size and weight of the image recording apparatus are inevitably increased for obtaining large-sized recorded images, insofar as the development of the latent image relies upon application of toner directly to the recording medium. This problem is serious particularly in the development of a color image, which requires a plurality of latent-image forming media, as well as a plurality of kinds of toner. The use of a plurality of media and a plurality of toners is undesirable also from the view point of maintenance and operation cost of the apparatus.
On the other hand, the system incorporating a digital photoelectric conversion device such as a CCD requires the original to be scanned mechanically by the photoelectric conversion device when the latter is composed of a one-dimensional array of photoelectric conversion elements. When the device is composed of elements which are arranged two-dimensionally, the elements have to be arranged with a high degree of density and fineness, in order to read a dense image with a high degree of resolution, with the result that the cost of the apparatus is increased undesirably. In addition, an external memory has to be employed in order to store the read image information. In addition, it is necessary to provide color filters on the surface of the CCD, when the image to be read is a color image. This further raises the cost of production of the apparatus of this kind.
An image recording system also has been known in which an image is converted into electrical signals by means of vacuum tubes, as in the cases of systems which employ an image orthicon or a vidicon. This system enables the original image to be read at a high speed and with a high degree of resolution without necessitating a fine arrangement of the reading elements. However, this system also requires an external memory such as a video tape for recording the read image. The external memory device, and the power unit for activating the vacuum tubes, are of considerably large sizes and weight, so that this system is not suitable for use where a high degree of handiness or portability is required.
Also known is an image recording system which relies upon silver halide photography. This system can record an image at a high resolution and enables the recorded image to be left on a film for a long time, thus allowing an image-recording portion such as a camera to be handled independently of the film and vice versa. This feature is very helpful because the user needs only to carry the image-recording portion, i.e., the camera. This system, however, is disadvantageous in that the film as the medium for carrying an image cannot be used repeatedly and in that a complicated system and troublesome work is required for developing the latent image by means of chemical agents such as a developer.